COM files in Windows 7 64-bit?

Index > Windows > COM files in Windows 7 64-bit?

Author

Thread

Falk

Joined: 16 Aug 2011
Posts: 2

Falk 20 Aug 2011, 21:23

I've just started with Assembly, and I found this code in a tutorial:

Code:

org 100h
mov ah,09
msg db "hello world!$"
mov dx,msg
int 21h
mov ah,08
int 21h
int 20h

In Windows XP 32-bit it displayed a nice MSDOS prompt with the text in it.
In Windows 7 64-bit I get this message:

Quote:

This version of the file is not compatible with the version of Windows you're running. Check your computer's system information to see whether you need an x86 (32-bit) or an x64 (64-bit) version of the program

Is there a way to make this code (or something similar) work in 64-bit?
I quite like the simpleness of this code, and I would like to wait a while before I start with all the Windows includes and the PE format.

20 Aug 2011, 21:23

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20761
Location: In your JS exploiting you and your system

revolution 20 Aug 2011, 21:27

You will need something like DOSBOX to run the old DOS programs in Win7. MS removed support for 16-bit programs so there is no other way other than using a DOS emulator.

20 Aug 2011, 21:27

me239

Joined: 06 Jan 2011
Posts: 200

me239 20 Aug 2011, 21:32

revolution wrote:

You will need something like DOSBOX to run the old DOS programs in Win7. MS removed support for 16-bit programs so there is no other way other than using a DOS emulator.

Beware though, DOSBox is meant for DOS gaming so don't be surprised if a lot of your DOS utilities and programs don't work.

20 Aug 2011, 21:32

DOS386

Joined: 08 Dec 2006
Posts: 1904

DOS386 21 Aug 2011, 02:07

Falk wrote:

Code:

org 100h
mov ah,09
msg db "hello world!$" ; !!! BUG !!!
mov dx,msg
int 21h
mov ah,08
int 21h
int 20h

The code is faulty as it
executes data Sad

Quote:

Is there a way to make this code (or something similar) work in
64-bit?

NO.

Quote:

I quite like the simpleness of this code, and I would like to wait a while before I start with all the Windows includes and the PE format.

PE works without includes too
Wink

... Otherweise, I recommend only
PE examples if you don't have DOS.

_________________
Bug Nr.: 12345

Title: Hello World program compiles to 100 KB !!!

Status: Closed: NOT a Bug

21 Aug 2011, 02:07

Falk

Joined: 16 Aug 2011
Posts: 2

Falk 21 Aug 2011, 09:23

I think that I'll just run in Windows XP/Virtual mode on Windows 7.

DOS386 wrote:

The code is faulty as it
executes data

As I understand it too, yes it does.
But it always works, so I let that one slide, as I believe I know what the problem is, and won't really build a major project based on this hello world Smile

Thanks guys.

21 Aug 2011, 09:23

Madis731

Joined: 25 Sep 2003
Posts: 2138
Location: Estonia

Madis731 21 Aug 2011, 14:26

You are *VERY* lucky that your code works, because this is what the CPU sees:

Code:

org 100h
mov ah,09
msg:push 6C65h
    insb
    outsw
    jc $+2+6Ch
    and [fs:si],sp
mov dx,msg
int 21h
mov ah,08
int 21h
int 20h

21 Aug 2011, 14:26

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum